On July 11, 2009, the Federal Court invalidated the patent claiming amlodipine besylate (Pfizer's NORVASC) on all grounds argued at trial: obviousness, selection patent, utility, sufficiency and non-compliance with section 53 of the Patent Act. In particular, the Trial Judge, Justice Hughes, held that the patent contained misstatements that were misleading and that sufficient intent to make such statements had been made out in the evidence. As a result, the Court concluded that there was a breach of section 53. (ratiopharm Inc. v. Pfizer Limited, July 11, 2009. Full judgment – 2009 FC 711.)
The patent at issue was the subject of two decisions under the Patented Medicines (Notice of Compliance) Regulations ("Regulations") where the Court had rejected allegations of invalidity. First, ratiopharm unsuccessfully challenged the patent pursuant to the Regulations (Pfizer Canada Inc. v. Canada (Minister of Health), 2006 FC 220, aff'd 2006 FCA 214, application for reconsideration dismissed 2007 FCA 407) before launching the present action to impeach the patent. (Consistent with recent Federal Court practice, the parties were able to reach trial less than two years after issuing the statement of claim.) Second, Justice Hughes had granted an application for prohibition under the Regulations involving the same patent and Pharmascience Inc. (relying in part on the first decision involving ratiopharm) (Pfizer Canada Inc. v. Canada (Minister of Health), 2008 FC 500).
The patent in issue, Canadian Patent No. 1,321,393, claims the besylate salt of amlodipine. The patent acknowledged that both amlodipine and several different pharmaceutically acceptable salts had been previously disclosed. The patent disclosed that the besylate salt showed a "unique combination of good solubility, good stability, non-hygroscopicity and good processability which makes it outstandingly suitable for the preparation of pharmaceutical formulations of amlodipine."
Before addressing the grounds of invalidity, the Court compared Pfizer's actual development work leading to the besylate salt and the patent disclosure. This comparison, and differences identified by the Court, would form the factual basis for a number of the invalidity attacks, including the section 53 attack, which provides that a patent may be invalidated in circumstances nearly akin to fraud.
The Court emphasized that there is an overriding duty under section 34 of the Patent Act to "correctly and fully describe the invention" and under section 53 "not to wilfully provide in the specifications more or less than is necessary so as to mislead."
In considering obviousness, the Court applied the recent Supreme Court decision in Apotex Inc. v. Sanofi-Synthelabo Canada Inc., 2008 SCC 61. The Court found that the inventors, when given the task of looking at amlodipine maleate, tried adjusting the formulation to find a suitable formulation (which was eventually found) and used salt screening, a "well known" process. The Court seemed influenced by the amount of work required to achieve the invention, noting: "[a]ll of this is routine for a person skilled in the art at the time. In the first set of salts screened the inventors found a few salts, particularly the sulphonic acid salts, including besylate, good enough, so they stopped there, why bother testing more." The Court also accepted evidence that a skilled person "would be motivated to test sulphonic acid salts in general and would have every reason to test the besylate salt as this had already been shown to offer advantages over other salts in terms of stability." The Court ruled that the patent was obvious.
In view of a possible appeal, the Court also addressed the other bases of alleged invalidity.
On the issue of selection, the Court questioned whether a "selection" patent is nothing more that another way of approaching obviousness. In any event, the Court found that the patent did not meet the criteria for selection patents, focusing on what the inventors actually did: "it is difficult from the face of the patent and unsupportable from the evidence to state that besylate is sufficiently superior to the other salts, for instance tosylate and mesylate so as to make it 'unique' or 'outstanding' or 'particularly suitable.'" As a result, the Court rejected the selection patent argument.
In assessing inutility, Justice Hughes noted his decision under the Regulations rejecting an allegation of inutility regarding the same patent (and Pharmascience) (Pfizer Canada Inc. v. Canada (Minister of Health), 2008 FC 500). However, he noted this decision was limited to "the patent alone," while he had evidence in the present case "beyond the patent." The Court characterized the promise of the invention as being that the besylate salt "has a 'unique' combination of features which make it 'outstandingly suitable' for pharmaceutical formulations." However, given that at least two other salts "were, depending on the formulations and circumstances, equally good or better" and that the maleate was also sold as a commercial product, the Court ruled that the patent lacked utility.
On sufficiency, the Court noted that its earlier finding of sufficiency (in the Pharmascience decision) was based on what was presented in the patent. In addressing the merits of the sufficiency attack advanced by ratiopharm, the Court did not consider whether the skilled person could practice the invention but whether the disclosure accorded with what was actually contemplated by the inventors. The Court found that the patent did not so accord, noting: "[a]s discussed earlier in these Reasons, there are many serious errors, omissions, insertions from elsewhere and departures in the '393 Patent in comparison with what the inventors contemplated."
The decision suggests that the language of section 34(1)(a) — "correctly and fully describe the invention and its operation or use as contemplated by the inventor" — may require that a Court compare the invention as disclosed by the specification with the invention as subjectively contemplated by the inventors. Sufficiency may not be limited to whether the specification provides enough information to allow the skilled person to know what the invention is and how to practice it.
Finally, the Court ruled that the patent did not comply with section 53 on three grounds:
- "omitting to mention the stability of the mesylate monohydrate and adding that it was unsuitable for tablet formulations;
- omitting the sulphonic acid test data showing mesylate, napsylate and tosylate to be stable, non-hygroscopic hydrates; and
- adding a statement that none of the salts outlined in EP167 had been found to satisfy the four criteria for pharmaceutically acceptable salts."
The Court ruled that the three pleaded matters were misstatements, were misleading and that sufficient intent to make such statements had been made out in evidence. It is unclear whether the Court made an express finding of intent to mislead or inferred such an intention from the surrounding factual circumstances.
The Court's decision has potentially far-reaching implications, particularly for selection patents. Parties attacking patents will attempt to minutely scrutinize a patentee's development history in the hope of turning up omissions, errors and alleged misstatements. Moreover, the emphasis on whether a specification has described the invention contemplated by the inventors may also fuel documentary and oral discovery of the patentee and the inventors.
Pfizer has appealed the decision.
Our articles and newsletters are informational only, and do not constitute legal or professional advice. To obtain such advice, please communicate with our offices directly.